N-Bromosuccinimide (NBS) Bromination of Anisole and p-Substituted Anisoles in 50% Aqueous Acetic Acid

Department of Chemistry, Loyola College (Autonomous), Madras-600 034 Manuscript received 15 October 1982, accepted 3 August 1983 The kinetics of bromination of anisole and p-substituted anisoles by NBS was investigated In the presence of HClO4/NaOAc and Hg(OAc), in 50% aq. HOAc. Pure NBS bromination can be followed by initial addition of Hg(OAc), which prevents accumulation of bromine in the system. The reaction is catalysed by AgCIO4. Based on Hammett plot, the reaction constant is -7.85 for Ag+-catalysed bromination. As the water content in aq. HOAc is increased from 0-60% (v/v), the rate constant is found to increase 20 fold for PNA-NBS reaction. The product analysis of the PNA-NBS reaction catalysed by Ag+ was done by glc which gave 2-bromo-4-nitroanisole as the only product